It is well accepted by scientific authorities that living tissue can be made to grow in response to a gentle, sustained tensile force which, in the prior art, has generally been induced through a mechanical arrangement. This phenomenon has been demonstrated in many kinds of living tissues including skin, bone, muscle, nerves, blood vessels, lungs and even in isolated tissue cultures. (See references attached in Exhibit A.) The physiological mechanisms which contribute to this universal property of living tissue have recently been reviewed. (See references attached in Exhibit A.) Furthermore, many useful medical devices have been developed which rely on this universal property of tensile force induced tissue growth. (See references attached in Exhibit A.) However, as mentioned, these prior art devices typically operate through a mechanically induced tensile force occasioned by hooks, pins, or other more invasive, complication prone surgical procedures for establishing mechanical procedures for establishing mechanical connections between which the tensile forces are created.
The inventor herein has himself previously invented a non-invasive, mechanical device for applying a sustained tensile force to a soft tissue or skin surface to thereby enlarge a patient""s soft tissue. The inventor has received patents on these various non-invasive devices and methods including U.S. Pat. Nos. 5,695,445 and 5,662,583, the disclosures of which are incorporated herein by reference. While the inventor""s work is continuing, he has engaged in rigorous clinical testing as a necessary predicate to receiving FDA approval which has confirmed the clinical effectiveness of his devices and methods in enlarging soft tissue including female breasts. More particularly, the device used in his clinical studies utilizes a low level vacuum to apply a tensile force on the skin surface of a breast, with an adhesive surface being used to seal the vacuum against the patient""s skin. This device takes the form of a bra-like appliance which is portable and aesthetically acceptable in that its presence is virtually undetectable as it is worn by the patient during her daily activities. These prototype devices being used are fully operational and have confirmed the effectiveness of a sustained tensile force in achieving soft tissue growth and enlargement.
As the inventor has continued his further work and development in this area, he has continued to seek ways to improve his devices with respect to their effectiveness, aesthetics, and comfort to a potential patient. One of the more difficult problems to solve with the inventor""s vacuum based devices has been the need to maintain the vacuum as the device is worn throughout daily activities and yet be so unobtrusive as to be undetectable to those around the patient and who may be in close proximity to her. The inventor has developed one such device in which a vacuum may be established as the patient begins her day, and then supplemented or even reestablished with a hand operated pump and valve mechanism should the vacuum become reduced to an unacceptable level or otherwise escape as the patient twists and bends her torso in her normal daily activities. However, even with this particular arrangement, the inventor has sought to further improve his device by developing an alternative means for delivering a distracting force and yet permitting the patient to twist and turn her torso as needed without the inconvenience of reestablishing or supplementing the vacuum needed to achieve the soft tissue enlargement. While the inventor had previously conceived of various mechanical arrangements for establishing and maintaining a tensile force in this application, and indeed received U.S. Pat. No. 5,662,583 issued Sep. 2, 1997 for several of them, these arrangements were subject to their own difficulties. For example, several of them required a somewhat elaborate arrangement of mechanical springs, wires, interleaved shell members, or other such mechanical and moving parts as to be fairly intricate and perhaps difficult to reliably implement. Another embodiment disclosed and claimed in the ""583 patent included utilizing an intermediate material which could be caused to shrink upon curing. While such a curably shrinking material could effectively create the desired tensile force, it may possibly require replacement of the once shrunk intermediate material at least on a daily basis as the patient would remove the bra and then reapply it, depending upon the material chosen and its capability for cycling, on demand. For these reasons, among others, the inventor has previously focused his activities on vacuum based devices.
In order to solve the potential difficulties with maintaining a vacuum in the vacuum based devices and the intricacies of the mechanical devices, the inventor herein has previously succeeded in conceiving and developing a further mechanical embodiment for creating the required tensile force in a soft tissue expander. More particularly, the inventor has conceived of utilizing a xe2x80x9cmemory materialxe2x80x9d which may be moved into a first physical arrangement for being adhered to the surface of the soft tissue desired to be enlarged, and then causing the memory material to transform into its second physical arrangement to thereby create the required tensile force. The first physical arrangement may be a non-memory arrangement and the second physical arrangement may be the memory arrangement. More particularly, the memory material may comprise one of the shape memory alloys, an example of which is Nitinol as disclosed in U.S. Pat. No. 3,174,851, the disclosure of which is incorporated herein by reference. Nitinol and some other related nickel-titanium or copper-zinc-aluminum methyl alloys have a xe2x80x9cshape memory affectxe2x80x9d that has been previously utilized in a number of useful medical devices. These include as an orthodontic arch where the arch is cooled and then placed in the patient""s mouth which warms it and moves it into a stressed shape to exert pressure on the patient""s teeth. Still other medical applications known to the inventor are as an expandable filter which is used in the blood vessels and as a bony anchor. These shape memory alloys or xe2x80x9cSMAxe2x80x9d have two crystalline phase forms with a transition temperature that can be set at approximately normal body surface temperature (approximately 30 degrees centigrade). At temperatures greater than this transition temperature, these alloys prefer the Austenite phase while at lower temperatures they prefer the Martensite phase. The Martensite phase crystal structure consists of a series of planes that may be readily displaced allowing the alloy to be easily deformed in nearly any direction. When the alloys are heated to a temperature at or above the transition temperature, the Austenite crystal phase is preferred which forces the planes to revert back into their original configuration. In effect, this hardens the alloys and forces them to spring back and restore their original or xe2x80x9csetxe2x80x9d shape. These alloys may also be activated by passing an electrical current through them. Thus, these metal alloys give the appearance of xe2x80x9crememberingxe2x80x9d their originally set shape. Cooling and heating these alloys below and above the transition temperature can be repeated thousands of times, each time changing the property of the alloy from being soft for fashioning into a second physical arrangement to rigid which causes them to spring back into their set shape or original physical arrangement. The set shape or xe2x80x9cshape memoryxe2x80x9d may be set by imprinting the desired form or shape into the alloy and then heating it to temperatures approximating 500 degrees centigrade.
In addition to shape memory alloys, certain plastics may also be engineered to move between a first physical arrangement and a second physical arrangement as a function of temperature, as known to those of ordinary skill in the art. These plastics may also be utilized as a xe2x80x9cmemory materialxe2x80x9d suitable for implementing the present invention.
In implementing these memory materials, the cups or domes described in one or more of the inventor""s previous patents could include some form of memory material in their fabric. Below body temperature, these domes would be soft and conformable to the shape and contour of the underlying breast or soft tissue surface to be enlarged. As the patient""s body temperature heats the domes and memory material, they will tend to revert and spring back to their previously imprinted xe2x80x9cmemoryxe2x80x9d of a deeper/wider dome. If appropriately adhered to the underlying soft tissue surface or skin, this reversion or xe2x80x9cspringing backxe2x80x9d of the memory material will then impart a tensile force to the underlying skin or tissue surface as would be effective for creating soft tissue enlargement in a suitable therapeutic regimen. Additionally, a small battery operated electronic circuit may be provided to activate and increase the tension of some of the fibers that would be set for a higher transition temperature. This would allow the bra to operate in an intermittent duty cycle in addition to maintaining a constant tension.
In order to appropriately distribute the tensile force while at the same time adhering the memory material to the underlying tissue, a layer of gel, or an air or other fluid filled bladder, may be an appropriate interface between the skin and layer of memory material, and an appropriate adhesive substance placed between the layer of gel and the underlying skin. As the inventor has disclosed in one or more of his prior patents, this adhesion could be effected with any one of a well known group of surgical adhesives which are known to bond appropriately to a skin surface without damage for extended periods of time. This may preferably be a layer of sticky silicone gel. Alternatively, the inventor has further conceived of implementing the principles of surface tension as a non-abrasive way of achieving this necessary adhesion. More particularly, a fluid may be placed on the gel layer, or on the patient""s soft tissue just prior to application of the bra, and the inventor has found that the forces attributable to surface tension are sufficient to maintain an appropriate adherence between the soft tissue and the gel as the memory material transitions physical arrangement to thereby impart the desired tensile force. Thus, the inventor has conceived of utilizing a memory material for mechanically inducing a tensile force in an appropriately chosen soft tissue site, as well as the concept of utilizing a thin layer of fluid as an interface for creating a surface tension to maintain adherence between a layer of gel or other intermediary layer to insure a distribution of the tensile force across the skin surface to thereby avoid undesired shear forces or other concentrating effects which might cause undesired abrasion or damage to the skin surface.
As a continuation of the inventor""s efforts, he has conceived of a further embodiment for applying a distractive force to an underlying soft tissue. This newest embodiment incorporates many of the advantages of the inventor""s prior embodiments while providing even greater control over the application of the force and dramatically improving its user friendliness including its physical size and contours. As can be appreciated, this aspect of the invention is important as its appearance as it is worn can be in an area of a person""s physique ordinarily considered to be private, i.e. such as a bra over a woman""s breasts.
In the inventor""s newest embodiment, a thin expandable rubber-like membrane that can espouse the contours of the small relatively flat tissue at rest and can stretch and expand to the contour of the enlarged distracted tissue. (Breast in the most common application but face might be an emerging one) is provided as well as an expansion mechanism or frame that is mechanically linked to the membrane and can stretch it to form a dome-like structure. In one version of this newest embodiment, a membrane is provided both above and below the frame, and may encapsulate it.
These newest embodiments provide a quantum leap in the practicality of the external tissue enlargement device. By eliminating the vacuum components, some of the constraints of the bladder rim (forces, pressures and areas in some combination and fashion still need to be equilibrated), and the need for multiple cup sizes, patient compliance, public acceptance and cost will be greatly improved. For the breast enlargement application, this new embodiment will be as simple to use and not bulkier than a padded bra.
Another related application of tension induced soft tissue generation is the rejuvenation of the aged face. Modern plastic surgery has realized that in facial rejuvenation, a face fill is just as important as a face lift. In other words, plumping up the face and restoring the subcutaneous fat atrophy associated with aging is nearly as effective as a face lift. Cosmetic surgeons currently fill up the wrinkle lines with fat grafts or collagen injections and significantly improve the facial stigma of old age. A wrinkle patch that induces tissue growth under the wrinkles or a rejuvenating face mask that fills up the lost fat are potentially very useful applications of this technology of tension induced tissue growth.
This newest embodiment aims to further refine the design of the mechanical expansion frames found in the inventor""s prior patents and to disclose the use of positive fluid pressure (gas or liquid) as the transducing force that can be used to expand these frames and create the necessary distractive force. As these tissue expansion frames expand, they are capable of rising from relatively flat surfaces to progressively deeper dome-like shells. When these novel types of frames are mechanically connected to the surface of the tissues (either through adhesives, through surface tension effect, or otherwise), their expansion pulls up the tissues, inducing a distractive force which causes them to grow.
Fluid pressure, however, is isotropic and will cause a simple inflatable structure to expand in all three dimensions, opening up like a balloon. The desired effect, on the other hand, is that of inducing a flat frame to rise as a three-dimensional dome-like shell. In other words the leaflets of the frame should not open up; rather, the desired expansion should induce the frame to keep a relatively even thickness forcing it to spread out only in two dimensions. By circumferentially constraining the frame either at its edges or though its inherent tailored design, the induced surface spread should cause it to rise as a dome-like shell. The three-dimensional surface contour of the dome, its excursion, and the force of deformation depend upon the fluid pressure applied and the mechanical design of the inflatable structure. Under the effect of positive fluid pressure, the rising and progressively deeper dome-like shell pulls up and distracts the tissues that are mechanically connected to its concave surface, inducing them to grow.
The main subject of this newest embodiment is the concept of a frame, which, in its resting state, can espouse the surface contour of the body part to be enlarged. This frame is connected to the underlying tissues either through a glue or layer of adhesive or through surface tension effect. A compliant expandable membrane may be additionally used to serve as the interface and the mechanical link between the frame and the surface of the tissue to be distracted. Although, other means for securing the underlying soft tissue to the frame may be used. For example, surgical attachment may be used. The frame is designed such that it can be inflated and under the effect of internally applied positive fluid pressure it can rise into progressively deeper domes. The range of excursion could stretch from flat to a nearly spherical surface in order to maximize the amount of induced distractive force. Furthermore, the surface contour of the expanded frame may be designed such that it can deviate from the perfect sphere as it expands into a dome. This is needed to evenly expand a complex surface, or to differentially expand certain areas relative to others. (i.e. from flat to tear drop in the case of a breast or more complex surface contour in the case of a full face). The force and extent of elevation of this frame can be gauged by the amount of fluid pressure applied. This frame will need to distribute the counterforce of distraction through its rim pressing against the tissues at the periphery. Therefore, as in the previous inventions, there is a need to equilibrate the pressures, forces, and/or the surface areas of the frame in relation to the contact surface area of the non-expanding surrounding rim.
Fluids under positive pressure have many useful applications. The inventor is, however, interested in those that result in rigid dome-like shell structures as compared to the simple inflatable balloon or ring-like tire. Applications more relevant to the present invention are the inflatable self supporting dome-like structures such as the ones used to cover stadiums or the umbrella-like and shield-like antennae deployed in aerospace applications.
While fluids under positive pressure are used in medicine to inflate tissue expanders (inflatable silicone shells), these devices are internal. They are surgically inserted under the skin and they stretch it from the inside out instead of the external device described herein which can raise the surface of the tissue by pulling it up from the outside. Furthermore these common tissue expander devices inflate like simple balloons instead of converting a flat frame into a dome-like shell.
In the present invention, the required effects of positive pressure inflation are mostly linear (one-dimensional), or preferably mostly sheet like (two-dimensional) expansion of the frame instead of the inherent three-dimensional ballooning effect of unrestrained inflation. To achieve this dimensional restriction, the basic building block may include one or more of the following several alternative design options.
In its simplest form, the expanding frame consists of an airtight flat bladder made out of an inner and an outer expandable membrane interconnected by a network of non-expandable links. The mechanical properties, the thickness, and the tailoring of these membranes are adjusted such that with inflation, this bladder which cannot blow up like a balloon, will distort into a dome-like shell (see FIG. 1 and its description below). This might be a mechanically inefficient means of using pressure to pull up the tissues, but it is contemplated by the inventor that it would be effective in this application. Other more efficient designs might be used, at least some of which are described below and others of which would be apparent to those of ordinary skill in the art having once gained the benefit of the inventor""s disclosure herein.
The simplest building block for the mechanically more efficient design is the piston-in-cylinder or some sort of corrugated accordion bellows that can expand in only one dimension under the effect of applied fluid pressure. A two-dimensional expansion will result from linking these one-dimensional blocks at various angles. The simplest geometrical design could be considered to be that of repeating triangles. When each side of the triangle expands one-dimensionally, the result is a two dimensional stretch of the construct. If, in addition, the edges of the repeating triangular pattern are constrained and prevented from stretching, the frame is forced to rise as a dome. This is the structural basis for the geodesic dome design (see FIGS. 7aandb and the discussion below). A person of ordinary skill in the art of computer aided design knows that any complex three-dimensional surface can be reduced to a series of adjacent triangles. Expanding the sides of these judiciously designed array of triangles can induce a controlled and preferential distraction of any complex body surface that needs to be enlarged. Other geometric shapes and arrangements for the frame itself may be used, as is described in greater detail below. Additionally, the details of the structure used for the xe2x80x9clegsxe2x80x9d or struts which form the frame can be varied to provide other ways for restraining the frame movement as it is expanded in order to achieve the desired application of a distractive force.
While some of the principal advantages and features of the invention have been discussed above, a fuller understanding of the invention may be attained by referring to the drawings and description of the preferred embodiment which follow.